Behavior of Arrays.asList()

[Olivier Ledru]

Hi,
Just wonder why Arrays.asList() has this behavior when passing an int[] !?
Why asList take it as a single Object, and not as a regular array ?!

import java.util.Arrays;
import java.util.List;
 
import junit.framework.TestCase;
 
public class TestArrays extends TestCase {

  public void testAsList() {
  System.out.println("testAsList()");
  
    List<Integer> listAnonymInteger = Arrays.asList( 1, 2, 3, 4 );
    assertTrue(4 == listAnonymInteger.size());
    List listAnonym = Arrays.asList( 1, 2, 3, 4 );
    assertTrue(4 == listAnonym.size());
    
    int[] arrayInt = new int[] {1,2,3,4};
    assertTrue(1 == Arrays.asList(arrayInt).size());
    Integer[] arrayInteger = new Integer[] {1,2,3,4};
    assertTrue(4 == Arrays.asList(arrayInteger).size());
  }
}

[Taariq San]

Because an array is just a single object, or have I misunderstood you?

[ramesh maredu]

the primitive array int[] arrayInt = new int[] {1,2,3,4}, i think here it is considered as single array object.
But in case of wrapper array each elements are cosidered as objects,

I am also not sure about it, i came to conclusion based on retrun type of Arrays.asList method in both the cases generated by eclipse IDE.

 
 
       int[] arrayInt = new int[] {1,2,3,4};
        List<int[]> asList = Arrays.asList(arrayInt);
        assertTrue(1 == asList.size());
        Integer[] arrayInteger = new Integer[] {1,2,3,4};
        List<Integer> asList2 = Arrays.asList(arrayInteger);
        assertTrue(4 == asList2.size());

[Olivier Ledru]

Well, after reading http://java.sun.com/j2se/1.5.0/docs/api/java/util/Arrays.html#asList(T...) ,
Why int[] is not read as 'int...' but Integer[] is read as 'Integer...' ?
Nothing in the API point any difference on this.
Did I miss something ?

[Taariq San]

Originally posted by Olivier Ledru:
Well, after reading http://java.sun.com/j2se/1.5.0/docs/api/java/util/Arrays.html#asList(T...) ,
Why int[] is not read as 'int...' but Integer[] is read as 'Integer...' ?
Nothing in the API point any difference on this.
Did I miss something ?

Those are 4 different ints each shoved into Integer objects, that's 4 different objects, whereas arrayInteger is a single object, an array of Integers. If it's not a primitive it's an Object, that goes for arrays too.
[ June 03, 2008: Message edited by: Taariq San ]